The nitrogen – containing conventional A_IIIB_V semiconductor alloys, so called diluted nitrides (A_IIIB_V-N), have been extensively studied recently. Unusual properties of these materials such as a large band gap bowing coefficient b (40 eV for GaAs_1-xN_x with x < 0.1%) and a large conduction band CB offset (> 300 meV) come mainly from a large size difference between N (0.068 nm) and As (0.121 nm) and a large electronegativity of N (3.04) compared to Ga (1.81) and As (2.18). These features make A_IIIB_V-N alloys very promising for applications in lasers and very efficient multijunction solar cells. There are not much papers devoted to applying these materials in photodetector device structures.

This work presents the technology and properties of undoped GaAs_1-xN_x/ GaAs heterostructures used as active regions in the construction of MSM and PIN photodetectors. The atmospheric pressure metal organic vapour phase epitaxy (AP-MOVPE) was applied for growing MSM test structures with the nitrogen contents varied form 0.5 % to 1.74 %. The thickness of the absorption GaAs_1-xN_x layer was changed from 98 nm to 135 nm. The structural and optical properties of these structures were examined using high resolution X-Ray diffraction HRXRD, photoluminescence PL (T = 80¸ 250K) and photoreflectance spectroscopy PR (T = 300 K). The DQW (double quantum well) PIN test structure was grown by radio-frequency molecular beam epitaxy RF MBE. The undoped active region consisted of two 10.5 nm thick GaAs_0.99N_0.01 wells separated by 15.2 nm thick GaAs barrier layer was surrounded by undoped 200 nm thick GaAs and 100 nm thick p⁺-type GaAs from the top of the structure and by undoped 200 nm thick GaAs and 500 nm thick n⁺-type GaAs from the n-type GaAs substrate. The properties of the DQW active region were examined using PL measurements (T = 300 K). Chemical wet etching was used for active region delineated to obtain the 80 μm × 60 μm MSM and Ø 125 μm PIN islands. The Ti/Pt/Au and Cu/Au metallization was applied for multifinger Schottky MSM contacts with 1 μm/ 2 μm and 1.5 μm/ 3.5 μm finger width/ finger spacing. In the case of PIN device planar structure the Pt/Ti/Pt/Au and AuGe/Ni/Au metallization was used for the top ring contact to p⁺-GaAs and for the bottom contact to n⁺-GaAs, respectively. Dark and illuminated by different wavelength lasers (λ = 650, 780, 850, 904, 980 nm; excitation power 20 and 40 μW) DC current-voltage characteristics were measured under the bias changed from –5 V to 5 V. Based on the obtained results the main device parameters as a dark current and a spectral response were estimated for both MSM and PIN structures.

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2. Technology of high-efficiency solar cells utilising dilute nitride semiconductors
3. Photoluminescence of (In, Ga)(As, N) triple quantum wells - the effect of rapid thermal annealing
4. The nature of carrier confinement in quantum dashesof various cross-section shapes
5. Effect of the hydrostatic pressure on quantum dot - quantum well tunnel injection structures
6. Heterostructure Al_xGa_1-xAs/GaAs solar cells
7. Optical investigations of two dimensional electron gas in the AlGaN/GaN heterostructures